Alarm Disarms without using the app

Why does the system automatically disarm when I approach the building? This only seems to happen when my phone is on. I am not disarming the panel via the app, is this normal?

It appears that you are utilizing the Qolsys IQ Panel 2, is that correct?

If so, you may have the Bluetooth disarm feature enabled. If a phone is paired with the panel via Bluetooth and Bluetooth disarm feature is enabled, the panel will disarm once the phone can find the Bluetooth signal from the panel.

You can confirm this at the panel by navigating to Settings -> Advanced Settings -> Master User -> Bluetooth Devices -> Settings.